A comparative evaluation of dried activated sludge and mixed dried activated sludge with rice husk silica to remove hydrogen sulfide.

The aim of this study was to investigate the effectiveness of dried activated sludge (DAS) and mixed dried activated sludge with rice husk silica (DAS & RHS) for removal of hydrogen sulfide (H2S). Two laboratory-scale filter columns (packed one litter) were operated. Both systems were operated under different conditions of two parameters, namely different inlet gas concentrations and different inlet flow rates. The DAS & RHS packed filter showed more than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 45 to 90 s and 300 mg/L inlet concentration of H2S. However, the RE decreased to 96.87% with the EBRT of 30 s. In the same condition, the DAS packed filter showed 99.37% RE. Nonetheless, the RE was shown to have dropped to 82.09% with the EBRT of 30 s. The maximum elimination capacity (EC) was obtained in the DAS & RHS packed filter up to 52.32 g/m3h, with the RE of 96.87% and H2S mass loading rate of 54 g/m3h. The maximum EC in the DAS packed filter was obtained up to 44.33 g/m3h with the RE of 82.09% and the H2S mass loading rate of 54 g/m3h. After 53 days of operating time and 54 g/m3h of loading rates, the maximum pressure drop reached to 3.0 and 8.0 (mm H2O) for the DAS & RHS packed and DAS packed filters, respectively. Based on the findings of this study, the DAS & RHS could be considered as a more suitable packing material to remove H2S

STUDY ON THE REUSE OF ZAMYAD FACTORY WASTEWATER TREATMENT PLANT EFFLUENT IN IRRIGATION

Considering the population increase in the cities and also the increase of per capita water consumption in these societies, the use of treated effluents for the green area irrigation has been taken into consideration. Human ever-increasing needs to green area in municipal societies and on the other hand the limitations in water supplies cause a new review in wastewater reuse. Also making use of treated effluents in irrigation has some limitations including clogging of the soil porosities, increasing of the chemicals and toxic substances to plants and increasing the probability of groundwater pollution. In this research, considering the indicators using recognition of the effluent s quality, at the first stage compound samples of domestic wastewater treatment effluents of Zamyad Factory were taken. The samples were tested from the viewpoint of quality. Results showed that the indicator of Sodium Adsorption Ratio, Sodium Percentage, amounts of chloride, and electrical conductivity comparing to Food and Agriculture Organization and Department of the Environment of Iran standards were higher than the standard levels. Also parameters such as TDS, TSS, BOD, COD, anions and cations were in standard levels. Results also showed that the increase of some of the undesirable parameters was not related to the operation of wastewater treatment plant. Therefore, in order to make the standard effluent, different methods may be proposed and the most practical and economical one is dilution by using 50% mixing with raw water

Evaluating the drinking waters microbial flora of reverse osmosis treatment systems in kashan city during summer and autumn (2015)

According to the various difficulties of Distillation desalination system,currently the membrane technology such as Reverse Osmosis (RO) is more useful. High concentration of dissolve solids in supplying water resources in Kashan caused a bad taste and reduced the consumer�s desire for using such water,and often they used treated water in a way that at the conducting time of this study,20 centers treated the water by RO method in the city. Therefore,this study evaluated the microbial flora of produced drinking water of RO treatment system in Kashan city during summer and autumn 2015. In this study the census method have used and the sampling have done from all the RO water treatment centers of the city. Three input,output and after storage,samples have taken. The evaluation of the temperature,residual chlorine,TDS,the storage time,and RO membrane operation time in samples have done. The HPC test has done on the samples in the laboratory and the positive plates have identified in terms of bacterial spices. The tests have repeated in four months of the year from July to October. The results showed 95 residual chlorine in the input samples and the HPC test for these samples showed no contamination. The sample contamination after treatment and the tank were 8 and 15 respectively. In addition,the most contamination level have related to September,which the samples temperature in this month reach its highest level. The Pearson coefficient results showed that there was a significant relation between the Heterotroph colonies number and the residual chlorine and temperature parameters,which was consistent with Karami et al. in Kermanshah and Dobaradaran et al. in Esfahan studies. In addition,there was a significant relation between the Heterotroph colonies number and storage time and RO membrane operation time. © 2016,International Journal of Pharmacy and Technology. All rights reserved

Preparation, Characterization, and Application of N,S-codoped TiO2/Montmorillonite Nanocomposite for the Photocatalytic Degradation of Ciprofloxacin: Optimization by Response Surface Methodology

An N,S-codoped TiO2/Montmorillonite nanocomposite, as a photocatalyst, was synthesized in the sol-gel method and used for the degradation of ciprofloxacin (Cip) in an aqueous solution. N,S-codoped TiO2/Montmorillonte was characterized by powder X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and X-ray fluorescence (XRF) analyzes. A central composite design (CCD) was used to optimize the variables for the removal of Cip by the N,S-codoped TiO2/Montmorillonite. A maximum decomposition of 92% of Cip was achieved in optimum conditions. The band gap value for the nanocomposite was 2.77 eV. Moreover, with the use of nanocomposite in the four consecutive runs, the final removal efficiency was 66%. The results show that the N,S-codoped TiO2/ Montmorillonite under simulated sunlight irradiation can be applied as an effective photocatalyst for the removal of Cip from aqueous solutions

Hydrogen sulfide removal by Thiobacillus thioparus bacteria on seashell bed biofilters

The aim of this research is to achieve an efficient and cheap methods to remove H2S from the factories emissions. Four serial cylinders are designed, 40 cm in height and 15 cm in diameter each. They are filled with bivalve seashells with 63% porosity which contains Thiobacillus thioparus bacteria to the maximum height of 27.5 cm. By mixing phosphoric acid and sodium sulfide, H2S gas is released and its concentration is measured as mg m(-3) before injecting into the cylinders. A permanent measuring instrument is equipped to control the gas coming out of the cylinders. In order to prevent the outdoor environment from pollution, first the gas is sent through two activated carbon columns and then sent through a ferrous chloride scrubber. Finally it is burnt directly by flames. There were 550 sample readings in 15 weeks. The changes in the discharge of the air which carries the gas are considered between 1-12 L min(-1) and the concentration of the influent pollutant is considered between 1-140 mg m(-3). Also the humidity in the atmosphere is fixed between 77-93% and the optimum temperature required for growing of the microorganisms is retained between 20.5-30 degrees C. After feeding the system for three weeks the efficiency started to increase so that by the end of the final week of this research the efficiency reached to 90% with the discharge of 6 L min(-1) of the carrier gas. The results achieved from this research show that because of not using Filamentous bacteria, clogging did not occur in the biological system in biofilters. The amount of head loss in cylinder was only 2 mm water and during this research, head loss was the same due to unclogging of filter. On the other hand the traditional methods are expensive in terms of using chemicals, carbon recycling and using fuel and etc. Therefore researchers have started new studies in this field. The above mentioned method, according to high efficiency, inexpensiveness and easiness of control and maintenance is considered one of the best methods

Preparation, Characterization, and Application of N,S-codoped TiO 2

An N,S-codoped TiO2/Montmorillonite nanocomposite, as a photocatalyst, was synthesized in the sol-gel method and used for the degradation of ciprofloxacin (Cip) in an aqueous solution. N,S-codoped TiO2/Montmorillonte was characterized by powder X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and X-ray fluorescence (XRF) analyzes. A central composite design (CCD) was used to optimize the variables for the removal of Cip by the N,S-codoped TiO2/Montmorillonite. A maximum decomposition of 92% of Cip was achieved in optimum conditions. The band gap value for the nanocomposite was 2.77 eV. Moreover, with the use of nanocomposite in the four consecutive runs, the final removal efficiency was 66%. The results show that the N,S-codoped TiO2/ Montmorillonite under simulated sunlight irradiation can be applied as an effective photocatalyst for the removal of Cip from aqueous solutions

A comprehensive study (kinetic, thermodynamic and equilibrium) of arsenic (V) adsorption using KMnO4 modified clinoptilolite

The sorption of As(V) on manganese oxide coated zeolite (MOCZ) was investigated through batch study to explore the feasibility of removing arsenic from groundwater. MOCZ was characterized by scanning electron microscopy, XRD, FTIR spectroscopy, and point of zero charge (pH (PZC) ) measurements. The effects of process parameters such as contact time, adsorbent size, temperature and pH were investigated. Arsenic detection was carried out by atomic fluorescence spectrometer. Arsenate adsorption onto MOCZ followed the pseudo-second-order kinetic model with a correlation coefficient more than 0.99. Optimum removal of arsenate occurred within pH range of 6-10. The equilibrium data were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The maximum adsorption capacity calculated from the Langmuir and D-R models was 151 and 152.8 mu g g(-1), respectively, at 38 A degrees C. The activation energy of adsorption (E (a) ) was found to be 3.68 kj mol(-1), suggesting that the adsorption process may be physical sorption. Thermodynamic parameters: Delta H (o) , was 1.181 kj mol(-1); Delta S (o) , was -0.29 kj mol(-1), while the values of Delta G (o) were -83.9, -86.7 and 89.8 kj mol(-1) at 18, 28 and 38, respectively, suggesting endothermic and spontaneous process and a rise in temperature favoring the adsorption

Optimization and modeling of photocatalytic degradation of Direct Blue 71 from contaminated water by TiO2 nanoparticles: Response surface methodology approach (RSM)

In the current survey, the removal of dye from contaminated water was studied by photocatalytic degradation using TiO2 nanoparticles with respect to pH, TiO2 dosage, reaction time, temperature and initial dye concentration. TiO2 nanoparticles were investigated by XRD, FESEM and FT-IR. The RSM was chosen to study the composition effects of input independent factors and one dependent output response (removal efficiency). The P-value (2.2 x 10(-16)), F-value (1832), R-2 (multiple R-squared: 0.9985, adjusted R-squared: 0.9972), and lack of fit (0.432) indicate that the reduced full second order model is highly significant for dye removal by TiO2 nanoparticles. The maximum percentage removal of dye, 90.2, was achieved at optimum operating conditions including pH= 6.5, TiO2 dose (1.2 g L-1), contact time (67.5 min), temperature (40 degrees C), and dye concentrations (55 mg L-1)), respectively. The maximum removal efficiency was calculated to be 100, using regression coefficients derived from the model and the Solver "Add-ins". The results indicated that the TiO2 photocatalyst was very proper for the removal dye from contaminated water, and it had good efficiency in eliminating textile dyes